Why Raccoons Didn't Cut It as Lab Rats

Lab rats may have won the cage fight to become model animals
for research, but psychologists once looked to raccoons as the stars for
studying intelligence.

Black-masked raccoons served
as favored test subjects for several U.S. psychologists during the early 20th
century, because their supposed curiosity and intelligence was considered just
shy of that found in monkeys. Yet the furry scoundrels proved tricky to
maintain in large numbers, as opposed to the smaller rats that became the
darlings of labs.

Researchers complained about raccoons trying to gnaw through
their cage bars and occasionally escaping to hide out in the lab ventilation
systems. Even raccoon fans, such as New Haven veterinarian and eugenicist Leon
Whitney, hoped to make experiments easier by creating a breed "as docile
and reliable as the kindliest breeds
of dogs" in the 1930s.

"Leon F. Whitney's vision of breeding a more pliable
strain of raccoons strikes me as interesting, but it remained a fantasy,"
said Michael Pettit, a historian of science at York University in Toronto.

The raccoon
experiments eventually fell out of favor because of the practical challenges. But
their unpopularity also marked a move away from comparative psychology that
looked at many animal species to deduce human insights, and toward behavioral
studies focused largely on rats, Pettit said.

Pettit sifted
through published research papers, letters and photographs from the 1900s and
1910s to find out why raccoons failed to catch on as lab rats. His
findings are detailed in the September
issue of The British Journal for the History of Science.

Curious creatures

Raccoons acquired a reputation for "knavery" as
light-fingered pranksters in the public imagination around the
turn of the 20th century, because of their sensitive touch and curiosity. Many
served as semi-domesticated
pets in rural U.S. towns and in cities.

Some researchers who studied raccoons, such as Lawrence Cole
of the University of Oklahoma, became convinced the animals represented a
unique model of animal intelligence. He and others even suggested that raccoons
could hold mental imagery in their brains and learn through imitation.

Experiments, however, didn't show any evidence of raccoons'
imitation abilities.

Holding onto memories

Still, the raccoons demonstrated impressive lab results even
when they weren't eagerly pawing through the pockets of researchers who had
come to check on their cages.

One series of delayed-reaction experiments conducted by
Walter Hunter at the University of Chicago included 22 rats, two dogs, four
raccoons and five children, from Oct. 1910 until April 1912.

The test required the animals and children to correctly
identify one of three light bulbs that would briefly turn on. But there was a
twist: They had to remember which bulb had turned on after a certain period of
delay, during which Hunter tried to distract the animals with yelling. He
treated the children more gently by distracting them with drawing, stories and
questions.

Raccoons could identify the correct light bulb after a delay
of 25 seconds, which paled in comparison to dogs capable of tolerating a
five-minute delay. Rats could identify the correct light bulb after a delay of a
second.

But Hunter remained impressed by how raccoons could run
around during the delay and claw at their cages, while dogs and rats had to
keep their bodies pointed toward the correct light bulb. Unlike the other
animals, 89 percent of the correct identifications by raccoons took place when
their bodies had the wrong orientation. Only the children demonstrated a similar
capability.

Minds or
stimulus-machines

Findings such as
Hunter's led to huge disagreements about whether raccoons truly possessed minds.
Whereas Cole had said raccoons could hold mental images and ideas in their heads, Hunter rejected the idea and
instead suggested the animals relied on simpler "sensory thoughts"
within the muscles.

Their debate
represented a larger conflict surrounding the rise of behaviorism, which emphasized
how animals could learn behaviors through conditioning. A famous example comes
from Ivan Pavlov training dogs to salivate in response to certain stimuli
ranging from whistles to electric shocks.

Behaviorists
preferred observation of controlled and measurable behaviors, and saw animals
as stimulus-response machines. They disputed the notion that animals such as
raccoons could possess minds.

But even famed psychologist
John Watson (who started the field of behaviorism) admitted that the raccoon
experiments seemed scientifically valid, and he could not find a behaviorist
explanation for their abilities.

Living in the
borderlands

Such arguments faded
with the vanishing popularity of raccoon experiments. The most vocal advocates
of raccoon experiments also faced a problem of scientific reputation, because
they came from lesser universities compared with the rising behaviorists.

The rise of lab rats reflects both practicality and the need to have comparable experiments
for methodological reasons, Pettit explained. But he added the absence of
raccoons and other lab animals undoubtedly influenced the behavioral
experiments of that era, and shaped the science that followed.

"As a historian, I am interested in what kinds of
populations become invisible and come to represent everyone, and which are
studied for their own idiosyncrasies," Pettit told LiveScience in an
e-mail.

The situation did
not go entirely unrecognized, as evidenced in a 1949 address by Frank Beach, then
president of the American Psychological Association's Division of Experimental
Psychology. He complained about the lack of truly comparative animal psychology
and the relatively poor "rat psychology" that had taken its place.

Jeremy Hsu

Jeremy has written for publications such as Popular Science, Scientific American Mind and Reader's Digest Asia. He obtained his masters degree in science journalism from New York University, and completed his undergraduate education in the history and sociology of science at the University of Pennsylvania.